LT-1/30-30 cam

[jim cear]

Zip Products(Corvetteforum link) lists a 1964-65 365/375,1970-72 LT-1 solid lifter cam and states it meets "30-30" specifications. Does anyone know if this is a LT-1 or 30-30 cam as discussed in many threads here?

[John Perkins]

Re: LT-1/30-30 cam

What is the difference between the original 30-30 cam and the LT1 cam. Which one gives you better lowend torque?

[Duke W.]

Re: LT-1/30-30 cam

Unless they give specific OE part numbers, I would question what they are selling. The LT-1 cam (3972178) replaced all OE 30-30 applications (3849346) for service in the early seventies. Typical published specs for the 30-30 and LT-1 cams - duration at .050", centerlines, valve lift are as follows:

30-30 254/254, 110/118, 0.485/0.485
LT-1 242/254, 110/122. 0.459/0.485

The durations at .050" above the top of the clearance ramp - the number you should use to compare to hydraulic cams are 239/239 and 231/239. Actual total valve lift is less when you take into account clearance and actual rocker ratio, which is less than 1.5:1. The specified valve lifts are "gross theoretical" from the base circle at a 1.5:1 ratio.

The LT-1 cam inlet side uses the same lobe as the L-72 cam and the 30-30 lobe on the exhaust side, indexed four degrees earlier. The L-72 uses the same lobe on both inlet and exhaust as does the 30-30 cam - two lobes - three cams.

My recommendation is to buy a repro cam from Federal Mogul Speed Pro. Their catalog clearly indentifies all the vintage cams by specs and GM part number. Zip products is just a retailer. They don't make the cam and may not even know what it really is. Their description sure sounds ambiguous!

Duke

[Duke W.]

Re: LT-1/30-30 cam

The LT-1 cam is the best overall SB max performance street cam ever made that can use the OE valvetrain with 100 percent reliability and longevity. The 30-30 is a real low end torque killer without producing much more top end power.

The 30-30. retarded four degrees, is a good vintage racing cam - the additional overlap will respond very nicely to headers and open exhaust, but kills low end torque with manifolds and mufflers. The LT-1 cam's broader torque bandwidth pays excellent dividends in normal street and highway driving - anything but all out racing.

Additional data in my other post in this thread and a lot more in the archives.

Duke